Liu Jiarui

A STUDY OF HELIUM TRAPPING, BUBBLE STRUCTURES AND HELIUM MIGRATION IN TYPE-316L STAINLESS-STEEL UNDER HELIUM IMPLANTATION

Abstract Type 316L stainless steel was irradiated with 70–170 keV He + to a dose of 10 15 −1×10 18 ions cm −2 at 77–673 K. Post-irradiation annealing was carried out up to 1323 K. 2.5 MeV enhanced proton backscattering, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and conversion electron Mossbauer spectrometry (CEMS) are used to investigate the He trapping, bubble structures and the He release.

Stopping power of 100–600 keV F+, Ar+, As+, Br+ and Xe+ ions in silicon☆

Abstract The stopping power of 100–600 keV F + , Ar + , As + , Br + and Xe + ions in silicon have been obtained from measured range distribution obtained by NRA and RBS techniques. A deconvolution program was used in order to obtain true range distributions from the measured NRA excitation curves or RBS spectra. The total stopping powers were determined through fitting the projected ranges based on LSS transport theory to the experimentally determined projected ranges. After subtracting calculated nuclear stopping cross sections, the electronic stopping cross sections were obtained. These results indicate that the electronic stopping cross sections at low velocities may be described by the four-parameter formulae proposed previously and that deviation from the velocity-proportional electronic stopping is evident.

ELECTRONIC STOPPING POWERS DERIVED FROM RANGE MEASUREMENTS FOR IONS AT LOW VELOCITY

Abstract Electronic stopping cross sections for 19 F + in Pb 1− x Sn x Te and 19 F + , 40 Ar + , 75 As + , 79 Br + and 132 Xe + in silicon were obtained by range measurements. Depth profiles of F in Pb 1− x Sn x and Si were measured by 19 F(p, αγ) 16 O resonance nuclear reaction and those of Ar, As, Br and Xe were determined by RBS. In order to obtain the true range distribution from the measured NRA excitation curves or RBS spectra, a deconvolution program was developed using a reference function, the Edgeworth distribution function, and parameter optimization process. By forcing a fit between the experimentally determined projected range and that calculated with the range statistics program the total stopping power was obtained. After subtracting the nuclear stopping power the electronic stopping power was derived. The electronic stopping power can be described by a four-parameter formula.

ION-BEAM MIXING - A NEW METHOD IN THE STUDY OF METASTABLE SUPERCONDUCTORS

Abstract A newly developed ion beam mixing technique was applied to the study of the superconductivity of AlSi alloys. The highest superconducting transition temperature T c is 7.53 K for Al-40 vol. % Si. The dose dependences of T c , Δ T c and R 0 reflect the mixing process and suggest that disorder might be the reason for T c enhancement.

Superconductivity of AlSi alloys formed by ion beam mixing at liquid helium temperature

Abstract Ion beam mixing of multilayered Al/Si films at low temperature ( T c and residual resistance R 0 were measured in situ after a succession of Ar ion bombardments at varying doses. The results showed that the samples within different ranges of Si concentration had different types of dose-dependence. At high doses, both R 0 and T c reached saturation. The normalized saturated resistance variation ΔR 0 / R 0 increased with increasing Si concentration, whereas the saturated T c rose to about 6.5–7.5 K for all samples within 16–40 vol% Si. After warming up to room temperature, T c decreased to about 3 K. It is proposed that the T c enhancement in AlSi alloys can be attributed mainly to the disorder induced by low temperature ion bombardment and stabilized by the Si atoms.

Depth profiling of hydrogen in solids by elastic recoil detection with 19f ions

The hydrogen depth profiling in solids has been done by elastic recoil detection (ERD) technique with multicharged 19F ion beam from a small Tandem Accelerator of 2×1.7MV. Details of the experimental technique are described. The depth resolution of about 230A in the near-surface regions (similar 5000A) is much better than that of ERD technique with 2.5MeV He beam and heavy ion beam of 30MeV.

Charge exchange into excited states in collisions between noble gas ions and atoms

Experimental resutls obtained demonstrate that there are two processes of excitation in every collision system: one is an one-electron capture into excited states, the other is a direct excitation of projectile and target by projectile ion impact. From the comparison of the emission cross sections between the two collision systems, we find that the potential energy defect and the velocity of incident ion are very important factors in emission cross sections, and a competition process of these factors in collisions occurs.

INFLUENCE OF TEMPERATURE ON HE-IMPLANTED STAINLESS-STEEL

Abstract Helium ion implantation (30–170 keV) into SS 316L at doses of 1014−5×1017 cm−2 at temeperatures of 77–673 K was investigated with enhanced proton backscattering, TEM and microhardness measurement. The influence of temperature on He trapping, He bubble lattice formation, bubble growth and coalescence, and microhardness was studied.

XPS study of ion irradiated Cu/SiO2 interfaces

XPS study was carried out on Cu/SiO2 interface following the irradiation of 6.0 MeV Si ion beam. The chemical shift in the copper spectra reveals for the first time the existence of a chemically bonded structure in the interface region resulting from ion irradiation.

REGROWTH OF MBE-GAAS FILMS ON SI SUBSTRATES BY HIGH-ENERGY ION-IMPLANTATION AND SUBSEQUENT ANNEALING

4.2 Me V 7Li channeling technique, laser Raman scattering spectrometry, and TEM have been utilized to study the regrowth of MBE-GaAs films of similar μm thick on Si substrates by Si+ implantation (0.6-2.6 MeV) and subsequent rapid thermal annealing. The results showed that crystalline disorder was greatly reduced in the recrystalized layers especially at the interface.